Effects of neuromedin B and GRP-10 on gastrin and insulin release from cultured tumor cells of a malignant gastrinoma

A study relating to gastrin release from gastrinoma cells by neuromedin B and C-terminal decapeptide of gastrin releasing peptide (GRP-10) has not yet been reported. Therefore, we studied the effects of neuromedin B and GRP-10 on gastrin release from cultured dispersed cells prepared from both the primary tumor in the pancreas and the metastatic tumor in the liver from a case of malignant Zollinger-Ellison syndrome. Both the primary and metastatic tumors obtained by a curative operation contained similar concentrations of gastrin and glucagon, whereas the primary tumor contained 10 times more insulin than the metastatic tumor. Gastrin release from cultured cells of both tumors was suppressed by 0.1 and 10 nM neuromedin B and tended to be suppressed by 0.1-10 nM GRP-10. However, insulin release from cultured cells of the pancreatic tumor was stimulated by GRP-10, but not by neuromedin B. These results might suggest that receptor function for the bombesin family peptides is abnormal in gastrinoma cells in both primary and metastatic tumors, and that a major source of insulin secretary cells is the contaminated normal islet cells in the primary tumor.     

Ecological studies ofRoparidia fasciata in Okinawa island I. Distribution of single- and multiple-foundress colonies

To compare between a single-foundress colony and a multiple-foundress colony at the pre-emergence state of a social wasp, R. fasciata, nest distributions and colony terminations were investigated in 8 sites with different environmental conditions. Marking experiments were also conducted in two sites at high wasp density.

1. Foundress populations were composed of single-foundress colonies in sites C, D and E, new environments where have recently suited for inhaviting, at low wasp density. In sites like A and B which were used year after year, at high wasp density, coexistence of multiple-and single-foundress colonies was observed.
2. From the marking experiment, nests initiated by a single foundress were more distant away from the nest where the original foundress emerged the fall before, compared to multiple-foundress nests which were initiated by multiple foundress.
3. Greater percentage of colony termination was observed in single-foundress nests than in multiple-foundress nests, and the colony termination in single-foundress colonies increased with the nest density.
4. Ant predation was the key factor causing the variation of the percentage of colony termination.

     

Effect of glucose on protein phosphorylation in rat pancreatic islets

Isolated rat pancreatic islets, incubated in the presence of extracellular ³²Pi to steady state ³²P incorporation into cellular phosphopeptides, were exposed to glucose for 10 min. Glucose (16.7 mM) significantly stimulated the phosphorylation of six phosphoproteins with molecular weights of 15,000, 35,000, 49,000, 64,000, 93,000 and 138,000. Mannoheptulose (16.7 mM) markedly inhibited glucose-stimulated phosphorylation of these six phosphoproteins. This protein phosphorylation might be important in mediating glucose-stimulated insulin release.     

A partial resolution and reconstitution of the ammonia-oxidizing system of Nitrosomonas europaea: role of cytochrome c554

The cell-free ammonia-oxidizing system of Nitrosomonas europaea was resolved into three major fractions: a membrane fraction containing cytochrome a1 and c-type cytochromes, a fraction with hydroxylamine-cytochrome c reductase and a cytochrome c fraction. The ammonia-oxidizing activity was reconstituted by the combination of these three fractions. The activity was more consistently reconstituted by adding Nitrosomonas cytochrome c554 to the membrane fraction. The hydroxylamine-cytochrome c reductase activity of the membrane fraction increased with the addition of cytochrome c554, but the oxidation of hydroxylamine to nitrite required a further addition of cytochrome c552. The ammonia oxidation by the membrane plus cytochrome c554 was affected by the concentration of phosphate and the addition of bovine serum albumin, spermine, or MgCl2.     

Beta-galactosidase-neuraminidase deficiency: restoration of beta-galactosidase activity by protease inhibitors

Beta-Galactosidase was partially restored by protease inhibitors, leupeptin, chymostatin and E-64 in cultured fibroblasts from three patients with beta-galactosidase-neuraminidase deficiency. Pepstatin did not activate this enzyme. Neuraminidase was not affected by any of these compounds in the culture medium. It was concluded that the activating effect was produced by a specific inhibition of thiol proteases.     

Limited autolysis of Ca2+-activated neutral protease (CANP) changes its sensitivity to Ca2+ ions

Ca2+-activated neutral protease (CANP) usually requires mM Ca2+ for activation. The sensitivity of CANP to Ca2+ is greatly enhanced by passing it through a casein-Sepharose column in the presence of Ca2+ ions. This conversion is ascribed to autolysis of CANP. The converted enzyme required 40 microM Ca2+ for 50% activation. Various properties of the converted enzyme were very similar to those of CANP-I, recently found in canine heart muscle. Names of "m-CANP" and "mu-CANP" are proposed for CANPs which require mM and microM order Ca2+ for inactivation, respectively.     

Immobilized mitochondrial electron transport particle for NADH determination

Nonphosphorylating electron transport particles (ETP) prepared from beef heart mitochondrion were immobilized in agar gel. The immobilized ETP showed an oxidase activity to both NADH and succinate. The immobilized ETP was reusable. An electrochemical device for the determination of either NADH or succinate was assembled consisting of the membrane-bound ETP and an oxygen probe. The response to succinate was specifically inhibited by the addition of malonate.     

Studies of a calcium-activated neutral protease from chicken skeletal muscle. II. Substrate specificity.

Calcium-activated neutral protease purified from chicken skeletal muscle hydrolyzed myofibrillar proteins, tubulin, spectrin, and oxidized insulin B chain, but hardly hydrolyzed synthetic or natural peptides.     

The course of resin canals in the shoots of conifers

The course of resin canals in stem cortex and the continuity between resin canals in leaves and those in stem cortex were investigated. The present paper is the first of three parts of the investigation. In this paper, fundamental features of resin canals and actual resin canal patterns in the Taxaceae, Cephalotaxaceae and Podocarpaceae are reported. From the observation of serial transections of shoots, composite diagrams and three-dimensional models of resin canal patterns are drawn. Central canals, if present, run vertically in stem cortex and sometimes divide, end blindly or unite each other. The distance between two adjacent central canals fluctuates rhythmically in connection with the vascular supply from the stem to leaves. The resin canal patterns of the families are classified into four types. Those ofTaxus, Nothotaxus and three species ofDacrydium belong to the Taxus type, those ofTorreya andCephalotaxus to the Torreya type, those ofDacrydium elatum, Podocarpus alpinus, P. elatus, P. elongatus andP. neriifolius to the Dacrydium type, those ofP. macrophyllus, P. nagi andP. koordersii to the Podocarpus type.